A Coast Guard spokesperson told Reuters that an employee had to sign the paperwork after visiting the facility Wednesday. Another California state inspector said that he had to sign an NDA and turn over his cell phone to enter the secret barge during its construction.

There has been speculation that the barge is a data center or retail hub specifically for Google Glass. But Bob Jessup, superintendent for a construction company that brought in 40 tight-lipped welders a day to work on the building last year, noted: “Who’s going to want to climb up in there? It’s really ugly.”